The present invention relates to a cartridge for the preparation of beverages and, in particular, to sealed cartridges which are formed from substantially air- and water-impermeable materials and which contain one or more ingredients for the preparation of beverages.
It has previously been proposed to seal beverage preparation ingredients in individual air-impermeable packages. For example, cartridges or capsules containing compacted ground coffee are known for use in certain coffee preparation machines which are generally termed “espresso” machines. In the production of coffee using these preparation machines the coffee cartridge is placed in a brewing chamber and hot water is passed though the cartridge at relatively high pressures, thereby extracting the aromatic coffee constituents from the ground coffee to produce the coffee beverage. Typically, such machines operate at a pressure of greater than 6×105 Pa. The preparation machines of the type described have to date been relatively expensive since components of the machine, such as the water pumps and seals, must be able to withstand the high pressures.
In WO01/58786 there is described a cartridge for the preparation of beverages which operates at a pressure generally in the range 0.7 to 2.0×105 Pa. However, the cartridge is designed for use in a beverage preparation machine for the commercial or industrial market and is relatively expensive. Hence, there remains a requirement for a cartridge for the preparation of beverages wherein the cartridges and beverage preparation machine are suitable, in particular, for the domestic market in terms of cost, performance and reliability.
The cartridge of WO01/58786 is substantially rectangular in shape. Consequently, the bed of beverage ingredients is also substantially rectangular in shape. The water enters the compartment containing the beverage ingredients through slots arranged down the long sides of the compartment. The infused beverage produced from the beverage ingredients is collected in a chamber located at one end of the cartridge. It has been found that portions of the water flowing through the cartridge will spend varying degrees of time in the bed of beverage ingredients depending through which slot the water enters the compartment. This can lead to uneven degrees of extraction and yield of the beverage ingredients both within one cartridge and between successive cartridges. In addition, during the pre-wetting step, where water is injected into the compartment to saturate the beverage ingredients, the degree of wetting is liable not to be uniform along the length of the cartridge.
JP2000093309A describes a cartridge having a cylindrical wall closed at upper and lower ends by aluminium film. In use, an inlet is pierced in the upper film to allow water to be injected into a central column from where it flows outwardly into the cartridge and filters downwardly through a coffee bed and then through a filter paper into a cylindrical collection chamber. An outlet for the beverage so formed is provided by piercing the lower film. The cartridge is relatively complex, in particular because it requires the presence of the cylindrical collection chamber which must be of a size at least equal to the filter paper. The requirement for the collection chamber at a lower end of the cartridge also increases the overall size of the cartridge. Further, use of the cartridge is relatively complex since the inlet and outlet of the cartridge must be formed in opposite ends of the cartridge.